In the related art, the vacuum cleaning device disclosed in Patent Document 1 for example, is known. In such a vacuum cleaning device, first, a decompression process of decompressing a vapor cleaning and drying chamber into which a workpiece is loaded using a vacuum pump is performed, and then a vapor cleaning process of supplying vapor of a hydrocarbon-based cleaning agent into the vapor cleaning and drying chamber to clean the workpiece is performed. Next, a spraying dipping cleaning process of cleaning, in particular, a gap or the like in the workpiece that is insufficiently cleaned in the vapor cleaning process by spraying the hydrocarbon-based cleaning agent to the workpiece or dipping the workpiece in the hydrocarbon-based cleaning agent stored in a dipping chamber is performed. When the cleaning of the workpiece is completely performed in this way, after the workpiece is conveyed into the vapor cleaning and drying chamber again, a drying process of further decompressing the vapor cleaning and drying chamber and evaporating a cleaning agent stuck to a surface of the workpiece is performed. Then, when the drying process is terminated, the workpiece is unloaded after the vapor cleaning and drying chamber is returned to atmospheric pressure, thus finishing the series of processes.
In such a vacuum cleaning device, the spent hydrocarbon-based cleaning agent (contaminant and the hydrocarbon-based cleaning agent stuck to the workpiece, hereinafter referred to as the spent cleaning agent) is sent to the vapor chamber to be reclaimed. Specifically, the spent cleaning agent sent to the vapor chamber is heated by an electric heater or the like to become vapor consisting substantially of only the hydrocarbon-based cleaning agent (distillation). Then, only the generated vapor of the hydrocarbon-based cleaning agent is used in the vapor cleaning process again, or cooled and condensed by a cooler using cooling water and then used in a spraying dipping cleaning process.
However, in the technology of Patent Document 1, the heat used to generate the vapor of the hydrocarbon-based cleaning agent in a vapor chamber is recovered by the cooler and discarded. In addition, a large amount of cooling water, about 200 L/min, is needed to cool the vapor, and a reservoir, a cooling tower, and so on, are also needed to increase the size of the device.
Accordingly, there is disclosed a technology, in the vapor cleaning device of atmospheric pressure, in which two-step heat exchange using a first heat exchange unit used to cool the spent cleaning agent in the vapor state generated in the vapor cleaning and drying chamber using water (liquid) as a thermal medium and a second heat exchange unit used to indirectly recover heat obtained by the first heat exchange unit is performed, and sensible heat obtained by the water (liquid) is supplied to the vapor chamber (for example, Patent Document 2).